Varies from mod to mod, but the consensus is 3 to 5 pics per post.
PG-13 (which SHOULD include partial nudity because that's the rule in the movies that are PG-13 but this board makes no sense so) no nudes, no exposed goodies.
No dicks either which is frustrating in the extreme because WE ALL HAVE ONE!! But as much as I have lobbied for some leeway in this matter I have been unsuccessful.